6.5 Creedmoor Barrel Length & Muzzle Velocity

16Jul

One of my closest friends has two 6.5 Creedmoor rifles made by Surgeon Rifles that he has tried a couple different barrel sizes on. He started with a 26″ barrel, because that is what Surgeon typically used but lately we’ve been shooting in more practical/tactical long-range competitions where you have to carry the rifle for miles every day … so he wanted to lighten the load. He was also planning to add a suppressor to his rifle, and a 26″ barrel + 9″ suppressor makes for a pretty long and cumbersome rifle. He eventually rebarrelled to a 22″ barrel, which he loves. Both of the barrels were big, heavy, Krieger #10 contours with 1:8 twists (and both rifles could shoot 10 shot groups under 1/2″ … mostly in one ragged hole).

He mentioned that he’d searched online to see what barrel lengths people were using for the 6.5 Creedmoor cartridge and get an idea for what kind of velocity he would be sacrificing, and saw a lot of debate … but not a lot of helpful information. The new Berger Bullets Reloading Manual said you could expect a change of about 25 fps per inch (see excerpt image). So he was expecting 100 fps loss, but that is not what happened. So we thought it’d be helpful to share what he found. He regularly shot each barrel length over an Oehler 35P chronograph, which is a professional grade chronograph and one of the most accurate ones made. He kept really good documentation on the velocities, and here is what he found.

6.5 Creedmoor with 26″ Barrel

This is the original configuration he tried, because it was the one Surgeon typically makes. Here are the velocities he found:

2805 fps – This was his muzzle velocity was out of a brand new barrel (without a suppressor attached)

2860 fps – His barrel sped up a little as the barrel broke in, and this is what his muzzle velocity was after 1,200 rounds out of the 26″ barrel (again, this was without a suppressor attached). This is the point where he rebarrelled, but he inspected the the barrel guys with a borescope with a professional gunsmith at Surgeon and based on the barrel wear they estimated this was about 1/2 way of the accurate barrel life.

6.5 Creedmoor with 22″ Barrel

2760 fps – This was the 1st velocities recorded with the brand new 22″ barrel (without a suppressor attached). He was ecstatic to see this, because he was expected more than 100 fps of velocity loss with 4″ less barrel, based on the estimates in Berger’s new reloading manual.

2805 fps – This is what he is now getting after 800 rounds, with the barrel completely broken in and no suppressor attached.

2833 fps – He has since started using a Thunder Beast 30P-1 suppressor with his 22″ barrel, and the added 9″ of length the suppressor adds has helped his muzzle velocity a little as well.

So ultimately, after he added the suppressor he only lost 27 fps with 4″ less barrel. That essentially means he only has 2/10 more vertical adjustment of a mil at 1,000 yards, and wind drift is virtually identical. In return he has a lighter, more maneuverable rifle … and he couldn’t be more happy with that trade.

24 responses to “6.5 Creedmoor Barrel Length & Muzzle Velocity”

He uses a 1:8 twist on all of his 6.5 Creedmoors. He honestly might go with a faster twist if Krieger offered one. One of the guys we really pay attention to is Todd Hodnett with Accuracy 1st, and he thinks overstabalization is a ridiculous concept. Here is a quote from Todd on the topic:

“I am a fan of fast twist rates, so let’s look at this very important component. Here are some considerations: barrel length and twist rate, long VLD-type bullets, heavier VLD-type bullets and shorter barrels may require a faster twist. I have tested this on several occasions and found the same answer with each test. In my opinion, the Greenhill Formula is a little outdated. Even though it may work for some types of bullets and some types of shooting, I believe we need much faster twist rates for extended long-range shots. This gives us better-retained gyroscopic stability as the bullet is reaching transonic flight and into subsonic flight, thus, better grouping capabilities as well as less loss of BC due to loss of stability. I even had a 1:7.8-inch twist on a .308.” – Todd Hodnett (Sniper Magazine, May 2012)

The only downside I’m aware of with going to a faster twist rate is that you will have more spin drift. “Faster spin rates will produce more gyroscopic drift because the nose ends up pointing farther to the side.” (View Source) However, the difference is usually very slight. For example, I ran the ballistics for a 6.5 Creedmoor with a 1:8 twist rate and the spin drift at 1200 yards was 10.5″. I changed the twist to 1:9 and the spin drift was 9.1″ at 1200 yards. If someone can shoot between those numbers at 1200 yards, I’d like to see it. So my thought process these days is to buy the fastest twist rate Krieger offers and go with it … especially if you are really pushing your gun beyond its supersonic range.

Thanks for your reply. I’m planning on having a surgeon scalpel built over the winter and was wondering if I should go with a 8″ twist or a 8.5″. or if it even matters. I thinking has been to go with the 8, and after reading your post, I’m thinking of sticking with a 8″ twist over an 8.5. How much do tighter twists affect muzzle velocity? Any insight on that? How much slower will an 8 be over an 8.5″. Thanks.

I recently gave my wife [ who has won 1st place at the Texas Trophy Hunters Extravaganza ] a Lady Savage 6.5 Creedmore and I worried about the shorter barrel. I think I will have a suppressor installed and see if that doesn’t help her MV.
CRaTXn cratxn@me.com

You should try it out. You’ll probably recover a little muzzle velocity. It is effectively extending the barrel, although most suppressors are 30 caliber and not 6.5mm … so it isn’t exactly the same as a longer barrel.

From what I’ve heard the 6.5 Creedmoor was originally designed for a shorter barrel. One of the lead guys on that project has even said that 22 inches is the ideal barrel length for a 6.5 Creedmoor … he was very adamant on that point. Not 24″ or even 23″ … 22.0″. My friend now has a few 6.5 Creedmoor barrels. He has two rifles chambered on Surgeon Actions (one pictured here and the other in a McMillan A5, but he prefers the AICS). He also has a few barrels in his safe that are already chambered. All of them are 22″ … he couldn’t be more happy with his choice to go shorter.

Just pointing out, that Berger was actually kinda spot on. They say 25 fps loss per inch from a 24 inch barrel. So that could be accurate if you make the assumption that there will not be much significant gains from 24″ to 26″

Our barrel change was 26″ to 22″ (not 24″). So that is 4 inches of difference at 25fps/inch, which should equate to 100fps. We experienced 55fps. That’s the point I was making. None of my results were for a 24″ barrel. I think that’s where you got confused.

I just had a 6.5 Creedmoor built on a &00 action with a 1-7 Douglas barrel. Developing loads right now. So far I am getting good groups with with Cutting Edge MT bullets with IMR 4350. Would appreciate and recommendations.

Hey Dane, thanks for sharing! The guys I know shooting 6.5 Creedmoor all use the Hornady 140gr AMAX Match Ammo. They publish that load on the box (one of the things the cartridge designer insisted on). The specs on the box say it is 41.5gr of H4350 and a Fed 210M primer. But Hornady’s 9th Ed Reloading Manual says the max load for H4350 is 40.9gr … So that is a hot load. But it seems to group well for everyone I’ve seen shoot it.

All it tells me is that its a well written article with nice pictures.
At best its anecdotal evidence from two data points, not anything better than a forum post that says “I had one barrel that did this, and another that did that”…

First, I’m not just some guy on a forum. If you’ve read many articles on my blog, you can tell I’m more detailed, data-driven, and transparent than the average keyboard jockey. Second, I use professional gear to collect the data (an Oehler 35p chronograph) and it’s based on a large sample size (at least 300 shots over a chronograph with 4 different barrels).

Ultimately, I’m just trying to post some data so that people have something to go on and can learn from my experience, without having to try it themselves. I guess if this isn’t detailed enough for you, start your own website and try to do better. I’d love to see more guys put in the time I do to help other shooters. Be sure to send me a link.

Cal,
Pay NO ATTENTION to Steve and people like him…. I am in the silent minority (I don’t think I’ve actually posted any comments on your blog in the past), but have read every single article on this site multiple times…. and I find your work to be invaluable and very well done…. a huge help for me (and so many other long range enthusiasts) in helping me with my current build, and with long range precision shooting in general.
As for you, Steve, I also eagerly await your FREE website created, financed, and written with your thousands of hours of selfless labor, blood, sweat and tears…… Really dude? C’mon and have some respect rather than casting stones…. put up or shut up, brother.

Will

January 20, 2015 at 3:17 pm

Excellent Article on a data starved cartridge! Definitely solidifies my Mega Maten 6.5CM 22″ JP barrel build. Would it be overreaching to ask what load was used? I’ll be thrilled if i can get an accurate load with that kinda heat behind it! Because Power Pro 2000MR shoots so well out of my .308 I’ll start there. Thanks and keep up the good work!

Hey, Will. These muzzle velocities are all for the Hornady 140gr AMax Match Loaded Ammo. They actually used to print the load data on the box, but I noticed the last couple cases didn’t have it printed on there anymore.

The specs on the box used to say it is 41.5gr of H4350 and a Fed 210M primer. But Hornady’s 9th Ed Reloading Manual says the max load for H4350 is 40.9gr … So that is a hot load. And I knew a couple guys who tried to reproduce the muzzle velocity they got with the Hornady loaded ammo, and they couldn’t do it with 41.5 grains of H4350. It was about 50 fps slower when they followed that recipe with the same components. So… I guess that might be why they took the recipe off the box. They may not be using exactly those specs.

HAD MY SAKO 85 REBARRELED INTO 6.5 CM WITH A 22″ KREIGER 1-8 TWIST.I DONT SHOOT MANY TARGETS USING ITMAINLY FOR FOR DEER STALKING AND VERMIN CONTROL.I USE 41.9 OF H4350 ACHIEVING A MV AVERAGE OF 2728 FPS.I FIND YOUR ARTICLES VERY INFORMATIVE AS THERE IS VERY LITTLE INFO FOR 6.5CM ON ANY OF THE ENGLISH WEBSITES.

Thanks for sharing the info, Geoff. Glad you find the content helpful.

Thanks,
Cal

GEOFF

January 29, 2015 at 6:17 am

THANKS FOR GETTING BACK CAL I FORGOT TO MENTION IAM USING 140 SST.THE SUPPLIES OF RELOADING COMPONENTS ARE VERY LIMITED TO SAY THE LEAST OVER HERE.WHAT I WAS WANTING TO KNOW WAS USING 222-50 CASES WITH THE COW METHOD.WITH THEM BEING SLIGHTLY SHORTER THAN THE 6.5CM WOULD THIS AFFECT THE BALLISTIC PERFORMANCE IN ANYWAY.ALSO WOULD YOU RESIZE TO 6.5 PRIOR TO USING THE COW METHOD OR AFTER.

CHEERS CAL I WOULDNT USAULLY BOTHER TRYING TO CONVERT DIFFERENT CASES INTO 6.5CM BUT SUPPLIES OVER HERE ARE VERY LIMITED TO SAY THE LEAST, AND GETTING VERY EXPENSIVE.WILL HAVE TO AWAIT FOR THE NEXT SHIPMENT TO THE SUPPLIERS.

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